Range timer



Jan. 12, 1960 G. H. WOTRING 2,

RANGE TIMER Filed Sept. 30, 1957 4 Sheets-Sheet l INVENTOR. GAYLORD H. Wommq Y 4 M; yaw

ATTORNEY Jan. 12, 1960 e. H. WOTRING 2,921,150

-RANGE TIMER Filed Sept. 50, 1957 4 Sheets-Sheet 2 INVENTOR. GAYLORD H. WoTRms ATTORNEY Jan. 12, 1960 e. H. WOTRING 2,921,150

RANGE TIMER Filed Sept. 30, 1957 4 Sheets-Sheet 3 IN V EN TOR.

GAYLoRn HWOTRmG BY ATTORNEY Jan. 12, 1960 s. H. WOTRING RANGE TIMER 4 Sheets-Sheet 4 Filed Sept. 50, 1957 INSULATION INVENTOR.

GAYLORD H. Womma BY ATTORNEY United States Patent RANGE TIMER Gaylord H. Wotring, Morrison, Ill., assignor to General Electric Company, a corporation of New York Application September 30, 1957, Serial No. 686,901

20 Claims. (Cl. 200-38) My invention relates to time switches and more particularly to time switches known as. range timers used to control the oven of an electric range.

Range timers now often include means for setting the stop time i.e., the time at which the oven is turned off, and means for setting the cooking period, i.e., the number of hours that the food is to be baked or cooked. In this way the housewife need not compute the start or oven turn-on time which is automatically set to the correct value by the timer when the stop time and cooking period are properly set.

Reliable and inexpensive range timers of the above type which are foolproof in the sense that they inherently prevent impossible settings from being made, are described and claimed in US. Patent 2,689,005, Schroeder and US. Patent 2,702,322, Truesdell both assigned to the present assignee. The range timers disclosed in these patents either have a rotating point of reference for step time indication or have a single shaft for setting both the stop time and the cooking period. They also have a self-cocking switch actuating mechanism and a selferasing indication of remaining cooking time in the cooking period. The rotation of the stop time reference point is sometimes confusing to the housewife while the use of a single shaft for setting both the stop time and the cooking period requires that the stop time be set before the cooking period.

Range timers which have separate shafts for setting the stop time and cooking period as well as a fixed reference point for stop time indication have not heretofore generally been foolproof or have not provided a self-cocking switch actuating mechanism or a self-erasing cooking period indication. Those few timers which have attempted to provide all of these features have been so complicated in structure and gearing as to be unduly expensive.

Accordingly, an object of the invention is to provide a foolproof, reliable, and inexpensive range timer having independent means for setting the stop time and the cooking period with a fixed reference point for stop time indication and also having a self-cocking switch actuating mechanism and a self-erasing cooking period indication.

In general, in accord with the invention a range timer is provided having a rotatable control element whose axial movement controls the operation of a switch. The axial movement of this control element is responsive however to its rotational position relative to a coaxial. stop time setting cam. A first manually operable setting means is provided for rotating the stop time setting cam and a second manually operable setting means is provided for rotating the control element in angular re-- lation to it. Motor driven means are also provided for engaging the control element when it is in one axial position and for rotating the control element at a fixed speed until it reaches an angular location relative to that of' the stop time cam at which location the element moves axially to operate the switch.

In accord with further features of the invention a ro- 2,921,150 Patented Jan. 12, 1960 tatable time indicator is mounted on each of the setting shafts and the rotation of the control element under the influence of the motor driven means produces the desired self-erasing cooking period indication. In addition, the axial movement of the control element during the setting operation actuates a switch cocking mechanism whereby the initial engagement of the motor driven means with the control element triggers the cocking mechanism to close the switch. Moreover, the control element and cam are constructed to provide an intermediate axial position of the control element when the cam and element have a predetermined relative angular location in which position the switch remains closed regardless of the continued operation of the motor driven means.

In accord with another feature of the invention the timer is made foolproof by virtue of special gearing which insures that the angular position of the cooking period setting shaft will always be representative of the angular difference instantaneously existing between the cam and control element. In accord with a further specific feature of the'invention, this special gearing includes a planetary type differential mounted on the cooking period setting shaft.

The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, together with further objects and advantages thereof may be easily understood by referring to the following description taken in connection with the accompanying drawing in which,

Figure 1 is a front view of a range timer embodying the invention;

Figure 2 is a bottom view of the range timer of Figure 1;

Figure 3 is an exploded perspective view of the various gears located between the front and back plates of the timer of Figure 1;

Figure 4 is a front view of the mechanism of the timer with the front plate removed;

Figure 5 is a perspective view of the switch setting and actuating mechanism of the timer;

Figure 6 is a rear detail view of a switch control element in the "switch setting and actuating mechanism of the timer; and

Figure 7 includes four side views, 7a, 7b, 7c, and 7d, of the switch setting'and actuating mechanism in four different operative positions, and a fifth view 7e showing a detail of the mechanism.

Referring to Figures 1 and 2 the invention is shown in one form as comprising a range timer 10 having a clock 11 and a pair of rotatable time indicators 12 and 13 one above the other at one side of clock 11. Clock 11 contains a central setting shaft 14 upon which are mounted the hour, minute and second hands 15, 16 and 17 respectively. Rotatable time indicators 12 and 13 are circular disks fixedly mounted on setting shafts 1i and 19 respectively. Clock shaft 14 and setting shafts 18 and 19 are all rotatably journalled in front and rear supporting plates 20 and 21 respectively with their front end portions extending through front plate 2i and terminating in manually operable setting knobs 22, 23 and 24 respectively.

The circular face of time indicator 12 is divided into 12 hourly designations 25 and is used to set the finish or stop time of the desired cooking period, and is hereinafter referred to as the stop time indicator. The

rotatable time indicator 13 has a semicircular portion of its face divided into six hourly designations 26 and contains, on the remainder semicircular portion, off and manual designations 27 and 28 to indicate to the housewife corresponding conditions of oven energization. Rotatable time indicator 13 is hereinafter referred to as a pair of windows 31, 32 exposing only small angular portions of these indicators.

The clock mechanism 35, manual setting means 36 and the switch cocking and actuating mechanism 37 are all carried by the front and rear supporting plates 20 and 21 with the clock mechanism 35 generally located in the region of clock shaft 14, the manual setting means 36 generally located in the vicinity of setting shafts 18 and 19, and the switch cocking and actuating mechanism 37 located intermediate the clock mechanism 35 and the manual setting means 36. An oven controlling switch 38 is mounted on rear plate 21 directly behind the switch cocking and actuating mechanism 37. An electric motor 39 is also mounted on rear plate 21 behind clock mechanism 35. As will be more fully explained hereinafter.

manually operable setting shafts. 1.8 and 19 function through setting means 36 to cock and adjust the time of operation of switch 38 while motor 39 functions'to drive the clock mechanism 35 and to energize the switch cocking and actuating mechanism 37. Shaft 19 also functions to permit direct manual actuation of oven switch 38 between open andclosed positions, and the motor 39 also functions to drive the cooking period indicator 13 as the cooking period progresses.

Referring to Figures 3, 4 and the construction of the clock, manual setting means and switch actuating mechanism will now be described, Clock mechanism 35 comprises a minute gear assembly 41 and an hour gear assembly '42 concentrically journaled on clock shaft 14. The minute and hour gear assemblies 41, 42 are geared together by a reduction gear assembly 43 pivotally supported between the frontand rear plates 20 and 21. Another gear 40 attached to the lower end of shaft 14 functions to rotate shaft 14 and control the movement of second hand 17. This second hand gear assembly 40 is driven from motor 19 through the motor output gear 45 and a gear train comprising gear 46, pinion 47, and gear 48. The minute gear assembly 41 isseparately driven from motor 19 through the motor output gear 45 and a gear train comprising gear 46, pinion 47, gear 49 and pinion 50. Y

Switch cocking and actuating mechanism 37 comprises a stop time control assembly 52, a switch control assembly 53 and a tripping assembly 54 all rotatably mounted coaxial with one another between the front and back supporting plates 20 and 21. Tripping assembly 54 preferably comprises a gear 55 having a tripping member 59 struck up therefrom at one radial location. Gear 55 is constantly driven at a fixed speed of one revolution in 12. hours by a gear train comprising gears 56, 57 and 58 driven by the reduction gear assembly 43.

Stop time controlling assembly 52 is arranged to be rotated in the setting direction of arrow 60 by setting shaft 18 through a gear train comprising gears 61, 62, 63 and 64. A metal leaf spring 65 carried by front plate 20 and having a detent 66 engaging the teeth of gear 61 prevents the rotation of stop time control assembly 52 in an opposite direction. Stop time control assembly 52 includes a cam 67 preferably formed integral with gear 64 and having a pair of diametrically opposed discontinuities such as arcuate recesses 74. Cam 67 is preferably composed of smooth, hard, low friction, preferably plastic material such as Bakelite or nylon.

Switch control assembly 53 comprises a control element 68 carried by a gear 69 on a hollow cylindrical sleeve or axle 70. Cylindrical sleeve 70 has a radial. arm 77 which serves to hold control element 68 against gear 69 and which carries an axially extending pivot pin 78 upon which control element 68 is pivoted. Control element 68 has a pair of diametrically opposed lugs 71 extending axially through oversized slots 72 in gear 69 whereby the control element 68 rotates together with the 4 I 7 gear 69. Lugs 71 also ride upon the surface of cam 67 and cooperate with recesses 74 as will be explained. Control element 68 also has an car 73 projecting in a direction opposite to lugs 71. Ear 73 is adapted to be engaged by tripping member 59 of tripping assembly 54 when control element 68 is in a rearwardly shifted control position. An elongated shouldered cylindrical pin 75 is slidably telescoped within hollow sleeve 70' and functions automatically to cock and actuate switch 38 in a manner to be explained.

Control assembly 53 is adapted to be rotated by setting shaft 19 through a gear train comprising gears 69, and 81 and a differential 76 including sun gears 82 and 83 rotatably mounted on shaft 19 and planetary gears 84, 85 and 86 mounted on a planetary arm 87 con nected to shaft 19. The rotation of shaft 19 is limited to an arc of about 270 by stop means comprising tabs 90 and 91 struck inward from the front plate 20'and engaging a radial projection 92 on planetary arm 87. A leaf spring 93 also attached to the rear surface of front plate 20 adjacent stop tab 91 functions to engage projection 92 and retain the planetary arm 87 in one limiting position corresponding to the manual or closed position of switch 38. A spiral spring 94 connected between shaft 19 and the rear plate 21 serves to bias the shaft in the forward direction to take up all the backlash in the gear train thus causing the cooking time indicator 13 to correctly indicate the time relation between switch control assembly 53 and stop time control assembly 52.

Referring to Figures 5, 6, and 7 the detailed construction and operation of the switch cocking and actuating mechanism 37 will now be described. The diametrically opposed arcuate recesses 74 of cam 67 are located on different circumferential paths and accommodate similarly located lugs 71 of control element 68 when they have the same relative angular location about axle 70. As best seen in Figure 7, recesses 74 each have a tapered side 102 extending in the setting direction 60 from its deepest central portion 103 and have a plateau or step 104 extending in an opposite or reverse direction indicated byarrow 95 from this deepest central portion 103. When lug 71 is in the deepest portion 103 of each recess 74 the control member 68' is in its forward axial position and car 73 is not in the path of tripping member 59 of trip gear 55. When lugs 71 are resting on the steps 104 of recesses 74 as in Figure 71) control element 68 is moved rearward to an intermediate position but ear 73 still does not move into interference with trip member 59. However, when control member 68 is moved up slope 102 onto the rear surface of cam 67, as in Figure 7c, control element 68 is moved axially to its rearward position in' which ear 73 moves into'the path of rotation of tripping member 59 whereby it may be engaged and driven by tripping member during the rotation of trip gear 55. it will thusbe seen that the axial position of control element 68 is dependent upon the rotational angular location of the control element 68 relative to cam 67. .Moreover, rotation of control element 68 in the setting direction 60 causes the control element to climb out of recess 103 onto the rear surface of cam 67, while rotation of the control element 68 in the reverse direction95 causes the control element 68 to climb onto the plateau portion 104 of cam 67.

Irrespective of whether lugs 71 of control element 68 are within the deepest portion 103 of recesses 74 or on plateaus 104 or riding on the rear surface 105 of cam 67, the rotation of cam 67 by means of setting shaft 18 also produces a corresponding rotation of control assembly 53 unless ear 73 of control element 68 is in actual engagement with trip member 59 of trip gear 55. It will be appreciated that this interfering engagement between ear 73 and trip member 59 will occur only when the control assembly 53 is in the axial position shown in Figures 70 and 7d and that continued rotation of cam 67 in the setting direction 60 after such engagement between car 73 and trip member 59 will cause lugs 71 to slide upon the rear surface 105 of cam 67 until the lugs 71 drop into recesses 74. It will also be appreciated that rotation of trip gear 55 in its usual reverse or driving direction 95 will effect this same movement-of control element 68 along the surface of cam member 67 as a result of the driving engagement between trip member 59 and ear 73.

Control assembly 5.3 is continually biased forward into engagement with cam 67 by means of a compression spring 106 and lever arm 107. Lever arm 107 has an aperture 108 accommodating hollow sleeve 71? and bears against a shoulder 109 in the rear end of sleeve 70. Compression spring 106 extends between the rear surface of lever arm 107 and a mounting bracket 110 fastened to rear plate 21. Sleeve 70 is rotatable within and slidable through the center of trip gear 55, while trip gear 55 is rotatably journaled in the rear plate 21. The forward end of sleeve 70 has a diametrical slot 111 in the plane of control element 68 within which a latch projection 112 of control element 68 extends. Actuating pin 75 extends within and along the axis of sleeve 70 and has a. front,

shoulder 113 which is adapted to be retained by the latch projection 112 of control element 68. Pressure from tripping member 59 upon ear 73 of control element 68 in the reverse rotational direction 95 causes the control element 68 to pivot slightly on pivot pin 78 and move the latch projection 1 1-2 out of the path of shoulder 1 13 thereby to release the actuating pin 75 for forward propulsion. However, when control element 68 is fully within recess portion 103, as illustrated in Figure 5, the forward end 115 of pin 75 bears against the rear wall of the hub of cam member 67 such that latch portion'112 of control element 68 falls into a latching engagement with shoulder 113 of pin 75 whenever the control assembly 53 begins to climb out of the recess up slope 102 as a result of the rotation of control gear 69 in its setting direction 60.

The switching assembly 38 is mounted directly behind actuating pin 75 between bracket 110 and the front and rear plates 20,21. This switching assembly 38 comprises a pair of stationary, insulating, terminal supporting plates 120 and 121 and a movable, insulating, switching plate 122. Stationary plates 120 and 121 carry two pairs of terminal members 123, 124, respectively carrying stationary contacts 127, 128, while switching plate 122 carries a pair of cooperating contact bridging members 131. Switching plate 122 has its central portion pivotally mounted on two laterally spaced pivot posts 133, 134 carried by stationary plate 120 so as to rock vertically about a horizontal axis represented by a line connecting these two pivot points. The upper swingable end 135 of switching plate 122 is arranged in the path of actuating pin 75 while the lower central portion of switching plate 122 is mechanically coupled to the lower end of lever arm 107 by means of a rod 136 and a surrounding spring 137. Connecting rod 136 extends freely through holes 138, 139 in the switching plate 122 and lever arm 107 respectively whereby the plate and arm may move toward each other against the force of spring 137. A backstop tab 140 is preferably bent out of bracket 11% to hold switching plate 122 adjacent pivot posts 133 and 134 and thus to limit the permissive lateral rocking motion of switching plate 122 in its open position.

By this construction it will be seen that when the control assembly 53 is in its forwardmost position with lugs 71 within recess portion 1113 of cam 67, as shown in Figure 7a, the lower end of lever arm 107 is likewise in its forwardmost position and carries the lower end of switching plate 122 forward to open the bridging members 131 from their respective pairs of stationary contacts 127, 128. When control assembly 53 resides in its intermediate position with lugs 71 upon the plateau surface 104 of cam 67, as shown in Figure 7b, the lower end of lever arm 1197 is moved rearwardly to an intermediate position thereby compressing spring 137 and causing the lower portion of switching arm 122 to rock about pivots 133 and 134 so as to cause bridging members 131 to engage their associated respective stationary contacts 127, 128. When control assembly 53 is in its rearmost cocked position with lugs '71 riding upon the rear surface of cam member 67, as shown in Figure 7c, latch portion 112 of control element 68 carries the shoulder actuator pin '75 rearward until it strikes the upper portion 135 of switching plate 122 thereby to cause the lower portion of the switching plate to rock forwardly on pivots 133, 134 and again open the bridging members 131, from their respective associated stationary contacts 127, 128. It will be seen that in this latter position the lower end of lever arm 107 is moved further rearward than when the control assembly is in its intermediate position, but this suflices only to compress spring 137 to a greater degree; the force of this spring being overcome by the force of actuating pin 75 upon the upper portion 135 of switching plate 122. When control assembly 53 is in its rearmost fired position, as shown in Figure 7d, actuating pin 75 is removed from the upper portion of switching plate 122 and the lower portion swings rearward under the force of lever arm 107 and compression spring 137 to close the switch 38.

In the operation of the above described timer for time controlled cooking, the stop time setting shaft 18 is manually rotated until the desired stop time is indicated by rotatable time indicator 1 2 through window 31. The cooking period setting shaft 19 is manually rotated until the desired cooking period is indicated by the rotatable time indicator 13 through window 32. Because of detent spring 65 stop time shaft 18 may be rotated in only one direction to rotate cam 67 in the setting direction 60. The cooking period is set by rotating shaft 19 in this same setting direction. In accord with important features of the invention, however, either shaft 18 or shaft 19 may be set first so that either the stop time or the cooking period may be set in any sequence; and if per chance too great a cooking interval is set, the cooking period may be readjusted to a lesser interval by merely rotating shaft 19 in a reverse direction to the setting direction.

As cam 67 is rotated in the setting direction 60 it carries with it and produces a corresponding rotation of control assembly 53 in the same setting direction 60. Rotation of the cooking period setting shaft in this same setting direction 60, however, causes the control element 68 to climb out of recess 103 along slope 102 onto the rear surface 105 of cam 67 and thereby shift the control assembly 53 axially rearward. As the control assembly moves rearwardly both lever arm 107 and actuating pin .75 are also driven rearwardly as a result of the engagement of lever arm 107 on the rear shoulder of sleeve 70 and as a result of the engagement of shoulder 113 of pin 75 upon latch portion 112 of control element 68. During the initial portion of this rearward movement, lever arm 107 causes switching plate 122 to rock in one direction under the force of compression spring 137, but as this rearward movement continues the rear end of actuating pin 75' strikes the upper portion of switching plate 122 to rock the switching plate 122 in an opposite direction and cock the switch 138 open.

It will be appreciated that the angular position of tripping member 59 of trip gear 55 represents a particular time of day and that the rotation of stop time setting cam member 67 alters the angular location of recesses 74 relative to the angular location of this trip member 59. The direction of rotation of trip gear 55, however, under the driving influence of clock motor 39 is opposite to the setting direction of stop time cam 67 or of control element 68. The particular angular location of recesses 74 thus represents a particular stop time which is indicated upon the rotatable time indicator 12 while the rotation of control element 68 in the setting direction causes the ear 73 of the control element 68 to move away from this preset stop time and to approach the clock time represented by the position of tripping memher 59 of trip gear 55. The angle between the location of lugs 71 and recesses 74 represents the number of hours in the cooking period. If the stop time cam 67 is set first and the position of recesses 74 is less than 6 hours away from the clock time represented by the position of tripping member 59, continued rotation of the control assembly 53 during setting of the cooking period will cause the ear 73 of control element 68 to engage the tripping member 59 and prevent further rotation of the control assembly beyond the actual amount of time available. Rotation of the cooking period indicator beyond 6 hours under any circumstances, is prevented by the striking of planetary arm projection 9 the location of lugs 71 and recesses 74 is equal to the I preset cooking period. Continued rotation of the stop time setting shaft 18 beyond this point causes the lugs 71 of control element 68 to slide along the surface of cam 67 toward the recesses 74 thuserasing the cooking period. However, because of the differential gearing between the stop time control assembly 52 and the switch control assembly 53, this erasure of the cooking period causes a corresponding rotation of the cooking period setting shaft 19 and of the rotatable time indicator 13 mounted thereon. Moreover, even though control ear 73 of control element 68 engages tripping member 59 during these manual setting operations there is no resultant component of force in a direction to cause pivotal motion of control element 68 and the actuating pin 75 remains latched to keep the switch cocked. This is because control element 68 has two lugs 71 extending through oversized slots in gear 69; and since assembly 53 can only be rotated by gear 69 acting through lugs 71, then whenever control element 53 is rotated by set shaft 19, control element 68 is constrainedto. hold its position with ear 112 against shoulder of pin 75 regardless of the force of ear 73 against tripping member 59.

Once the stop time and cooking period are properly set, the rotation of trip gear 55 under the influence of clock motor 39 causes the tripping member 59 to approach and engage the control ear 73 at a start time represented by the difference between the stop time setting and the cooking period setting. The initial rotation of tripping member 59 beyond this point of engagement causes the control element 68 to pivot and release the latching engagement between latch portion 112 and shoulder 113 of actuating pin 75. The actuating pin 75 is propelled forward under the influence of compression spring 137 acting through switching plate 122. Lever arm 107, however, is maintained in its rearward position by sleeve 70 of control assembly 53 and this causes the lower portion of switching arm 122 to rock rearwardly under the force of compression spring 137 thereby to close the switch 38 and turn on the oven.

The continued rotation of tripping member 59 by clock motor 39 causes a rotation of the control member 68 and a corresponding rotation and erasure of the cooking period indication on cooking period shaft 19 through the planetary differential gearing mounted on this shaft 19. This rotation continues until the stop time represented by the location of recesses 74 on cam member 67 is reached whereupon lugs 71 enter these recesses and came a forward axial movement of the control assembly 53 under the influence of compression spring 106 acting through lever arm 107. The resultant forward movement of the bottom end ofjlever arm 107 causes a corresponding forward movement of the lower end of switching plate 122 by virtue of connectingrod 136 thereby to again open the switch and shut off the oven. The forward axial movement-of the control; assembly 53 once again brings the latching portion 112 of control element 68 beneath the shoulder113-of'actuating pin 75 to prepare the assembly for'the succeeding setting operation.

From the above description it will be seen that so long as lugs 71 of control element 68 are within recess portion 103, the cooking period setting shaft 19 will always be in one particular location in which the rotatable time indicator will show the word off beneath window 32. In order to close the switch so as to be independent of the clock When manual control of the oven by means of the'thermostat switch is desired, it is necessary only to rotate this cooking period shaft 19 in a reverse direction from this off position to bring the manual abbreviation Man. under the window 32 and simultaneously to drive control element 68 onto plateau portion 104 of the cam 67. This causes the control assembly 53 andtt-he lever arm 107 to move'to their intermediate positions and close the switch as previously described. It is important that in this manual or intermediate position that'pin 75 be free to move forward without interference from latch portion 112 of control element 68 in order that switch armature 122 be allowed to close completely. This is effected by the nature of the recess in cam 67. When the main supporting lug 71 is onsurface 104, Figure 7b, the opposite lug is on the forward side of a hill 141 of step 104 of recess 74, as shown in Figure 7e. This hill 141 causes control element 68 to pivot forward moving latch portion 112 out of the way of pin 75. 1

Although I have described above one embodiment of the invention, many modifications may be made. For example, although I have shown the discontinuities in cam 67 preferably as recesses, it will be obvious to'those skilled in the art that they may be apertures or projections and that the control element 68 maybe modified to accomplish the camming functions provided by the surface of cam 67. Theqword discontinuity as used in the appended claims, therefore is intended to mean projections, recesses or apertures capable of providing the camming functions claimed. I also intend by the appended claims to cover all such modifications as fall within the true spirit and, scope of the claimed invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A timer comprising a rotatable cam, a first manually operable setting means for rotating said cam in one direction, an axially movable rotatable control element mounted coaxial with said cam, a second manually operable setting means for rotating said element in said one direction, cooperating means on said element and cam for moving said element between a first axial position when said cam and element have a same relative angular location and a second axial position when said cam and element have different angular locations, motor driven means for engaging and rotating said element at a fixed speed in a direction opposite to said one directionwhen said element is in said second axial position, and a switch operable in response to the axial movement of said element. 7

2. A timer comprising a rotatable cam, a first manually operable setting means including a first rotatable time indicator for rotating said cam in one direction only, an axially movable rotatable control element mounted coaxial with said cam, a second manually operable setting means including a second rotatable time indicator for rotating said element in either direction, cooperating means on said element and cam for moving said element between a first axial position when said cam and element have a same relative angular location and a second axial position when said cam and element have different angular locations, motor driven means for engaging and rotating said element at a fixed speed in a direction opposite to said one direction when said element is in saidsecond axial position, and a switch operable in response to the axial movement of said element.

3. The timer of claim 2 comprising gearing means interconnecting said first and second setting means for maintaining the angular position of said second rotatable time indicator always representative of the angular diiference instantaneously existing between the angular locations of said cam and element.

4. A timer comprising an axially movable rotatable control element, a first setting shaft for rotating said element, a rotatable cam mounted coaxial with said element, a second setting shaft for rotating said cam, directly engaging means on said cam and element for moving said element between a first axial position when said cam and element have a same relative angular location and a second axial position when said cam and element have different angular locations, a switch operable in response to the axial movement of said element, motor driven means for engaging and rotating said elementat a fixed speed when said element is in said second axial position, and gearing for maintaining the angular position of said second shaft always representative of the angular difference instantaneously existing between the angular locations of said cam and element.

5. The timer of claim 4 wherein said gearing means comprises a first gear train between said element and said first shaft, a second gear train between said cam and said second shaft, and differential gearing interconnecting said gear trains.

6. The timer of claim 5 wherein said differential gearing is located on said first shaft.

7. A timer comprising an axially movable rotatable control element having a control lug projecting from one side thereof, a first setting shaft for rotating said element, a rotatable cam mounted coaxial with said element and having a discontinuity in the side thereof for accommodating said lug, a second setting shaft for rotating said cam, spring means for biasing said element toward said cam whereby said lug rides on the side of said cam and said element moves between a first axial position when said lug and discontinuity have a same angular location and a second axial position when said lug and discontinuity have different angular locations, said cam being effective to forcibly move said lug and thereby said control element axially against the bias of said spring means upon the rotation of said element and said cam by said setting shafts, thereby to move said element from said said element is in said second axial position, and gearing first axial position to said second axial position as said lug and said discontinuity are rotated to different angular locations, a switch operable in response to the axial movement of said element, motor driven means for engaging and rotating said element at a fixed speed when means for maintaining the angular position of said second shaft always representative of the angular difference instantaneously existing between the angular locations of said cam and element.

8. A timer comprising a rotatable cam having an axial discontinuity in a side thereof, a first manually operable setting means for rotating said cam in one direction only, an axially movable rotatable control element mounted coaxial with said cam and having a control lug projecting from one side thereof and engaging said cam, a second manually operable setting means for rotating said element in said one direction, spring means biasing said element toward said cam whereby said element moves between a first axial position when said lug and discontinuity have a same angular location and a second axial position when said lug and discontinuity have different angular locations, said cam being effective to forcibly move said lug and thereby said control element axially against the bias of said spring means upon the rotation of said element and said cam by said setting shafts, thereby to move said element from said first axial position to said second axial position as said lug and said discontinuity are rotated todifferent angular locations, motor driven means for engaging and rotating said element at a fixed speed in a direction opposite to said one direction when said element is in said second axial position, and a switch operable in response to the axial movement of said element.

9. The timer of claim 8 comprising a time indicator rotatable together with said element and gearing means interconnecting said first and second setting means for maintaining the angular position of said time indicator always representative of the angular difference instantaneously existing between the angular locations of said cam and element.

10. A timer comprising a rotatable cam having an axial depression in a side thereof, manually operable means for rotating said cam, an axially movable rotatable control element mounted coaxial with said cam and having a lug on one side engaging said cam and moving into and out of said depression upon rotation of said element thereby to move said element between respective forward and rearward axial positions, manually operable means for rotating said element, said element having an ear projecting an opposite direction from said lug, a motor driven trip gear mounted coaxial with said element on the opposite side thereof from said cam and having an ear projecting toward said element in interfering relation with said control element ear when said element is in said rearward axial position, and a switch movable in response to the axial movement of said control element.

11. A timer comprising a cam, a control element and a motor driven trip gear all rotatably mounted coaxial with one another in the order named, said cam having an axial depression, said element being axially movable and having a lug on one side engaging said cam and moving into and out of said depression upon rotation of said element thereby to move said element between respective forward and rearward axial positions, manually operable means for independently rotating said cam and element, a switch, a pin coaxial with and latched to said element for actuating said switch upon axial movement and upon release from said latch, and means on said trip gear for engaging said control element during rotation of said trip gear to release said pin from said latch.

12. A timer comprising a switch having a switching arm pivotable at its central portion to open and close said switch, a lever arm extending alongside said switching arm and resiliently connected to one end of said switching arm, a control element in operative engagement with said lever arm, an actuating pin latched to said element and bearing against the other end of said switching plate, and motor driven means for engaging and moving said element first to release said pin to close said switch and subsequently to move said lever arm to open said switch.

13. A timer comprising a switch having a switching plate pivotable at its central portion to open and close said switch, a lever arm extending alongside said switching plate and resiliently connected to one end of said switching plate, a control element operatively connected with said lever arm and shiftable between first and second axial positions, manually operable setting means for moving said control element from said first to said second axial position, an actuating pin latched to said element and bearing against the other end of said switching plate when said element is in said second position and motor driven means for engaging and moving said element when said element is in said second axial position first to release said pin to close said switch and subsequently to shift said element from said second to said first position to move said lever arm to open said switch.

14. The timer of claim 13 wherein said manually operable setting means includes means for moving said control element to an axial position intermediate said first and second positions, said lever arm moving said cam and having a lug engaging said surface and moving into and out of said recess upon rotation of said element whereby said element moves between a first axial position when said lug is fully within said recess, a second axial position when said lug is out of said recess and an intermediate axial position when said lug is on said step, a switch, means connected to said control element for opening said switch when said element is in said first and second positions and for closing said switch when said element is in said intermediate position, manually operable setting-means for independently rotating said cam and element, and motor driven means for engaging and rotating said element relative to said cam when said element is in said second axial position and only when said element is in said second axial position.

16. The timer of claim 15 also comprising a pin latched to said control element and arranged to close said switch when released from said latch, said control element being pivotable to release said pin during the initial engagement and rotation of said element by said motor driven means when said element is in said second axial position.

17. A timer comprising front and rear supporting plates, a time control assembly rotatably mounted on said front plate, a tripping assembly rotatably mounted on said rear plate coaxial with said time control assembly, a switch control assembly having a control portion intermediate said time control assembly and said tripping assembly and a switch actuating portion extending rearward through said trip assembly, a switch mounted on said rear plate behind said switch actuating portion, said switch control assembly being axially shiftable within said trip assembly to actuate said switch, means included solely in said switch control assembly and said time control assembly and responsive to the rotation of said time control assembly for shifting said switch control assembly in one axial direction, and means responsive to the rotation of said tripping assembly for shifting said control assembly in an opposite axial direction.

18. A timer comprising a clock; a pair of setting shafts on one side of said clock; an axially fixed time control assembly, an axially movable switch control assembly and an axially fixed tripping assembly rotatably mounted coaxial with one another intermediate said clock and said shafts; gearing means for rotating said time control assembly by one setting shaft; gearing means for rotating said switch control assembly by the other setting shaft; gearing means for rotating said tripping assembly by said clock; a switch having a single switchingmember operable in response to the axial movement of said switch control assembly, and means responsive to the rotation of said trip and time control assemblies for axially moving said switch control assembly, said last mentioned means including directly engaging elements in said time control assembly and said switch control assembly which are effective to force said switch control assembly from one axial position to another axial position upon the adjustment of said time control assembly by said one setting shaft.

19. A timer comprising arotatable cam, a first manually operable setting means for rotating said cam, an axially movable rotatable controlelement mounted coaxial with said cam, means responsive to the rotation of said cam relative to said element for moving said element between forward, rearward, and intermediate positions, a switch, means coaxial with and latched to said element for cocking said switch open when said element is in said rearward position, motor driven means for engaging said element when said element is in its rearward position only to release said cocking means to close said switch, and means for closing said switch upon movement of said element to its intermediate position, said latter means being operative to release said element-from said cocking means.

20. A timer comprising a rotatable cam having a recess in one surface thereof, said recess having an in clined slope extending in one direction and a step extending in an opposite direction, an axially rotatable control element mounted coaxially with said cam and having a lugengaging said surface whereby said element moves between a first axial position when said lug is fully within said recess, a second axial position when said lug is out of said recess and an intermediate axial position when said lug is on said step, manually operable setting means for rotating said cam to move said element between said axial positions, a switch, means latched to said element for cocking said switch open when said element is in said second axial position, motor driven'means for engaging said element in said second axial position to release said cocking means to close said switch, means for closing said switch when said element is in its intermediate position on said step, and means on said step for releasing said cocking means from said element during movement. of said element to said intermediate position.

References Cited in the file of this patent UNITED STATES PATENTS "numb a. 4.... 

